There has been heretofore known a semiconductor physical quantity sensor in which an electrode is formed on an upper surface of a substrate and a diaphragm is disposed to be opposed to the electrode with a space in between (for example, see Patent Literature 1).
In this Patent Literature 1, the diaphragm bends in accordance with a physical quantity applied from the outside to change the capacitance of the semiconductor physical quantity sensor, and thus the semiconductor physical sensor is able to detect a change in the physical quantity by detecting the change in the capacitance.
Moreover, an insulator is provided over the electrode formed on the upper surface of the substrate, so that the insulator can check a short circuit due to contact of the electrode with the diaphragm. In this case, the insulator is deformed by a thermal process so that the insulator may not form ridge portions on edges of the electrode, and thus the upper surface of the insulator is made substantially flat.